Issued yesterday, the Pentagon’s annual report to Congress on China’s military and security developments contains a typically vast array of data, some publicly specified or confirmed for the first time. Among its 106 pages—arguably the most significant development is its unprecedented coverage of China’s maritime militia—the first official U.S. government assessment to call it out in public. This is a long overdue and welcome breakthrough: the shadowy but knowable force’s vanguard units are literally on the front lines of Beijing’s efforts to overpower its neighbors and advance its control over the South China Sea.

Together with the world’s largest Coast Guard, and with China’s Navy backstopping in an “overwatch” capacity, China’s maritime militia plays a central role in maritime activities designed to overwhelm or coerce an opponent through activities cannot be easily countered without escalating to war. The report terms this approach “low-intensity coercion in maritime disputes.” Leading elements of China’s maritime militia have already played frontline roles in manifold Chinese incidents and skirmishes with foreign mariners throughout the South China Sea. Such international-sea incidents of significant concern to the United States and its regional allies and partners include multiple contributions to furthering China’s sovereignty claims in the South China Sea.

China maritime-militia forces played a central role in the 1974 battle in which China seized the western Paracel Islands from Vietnam. More recently, as the report documents, they “played significant roles in . . . the 2011 harassment of Vietnamese survey vessels.” They harassed USNS Impeccable in international waters in 2009. They helped trigger the 2012 incident in which they ultimately supported other Chinese forces in seizing Scarborough Shoal from the Philippines. They engaged in reconnaissance and sovereignty patrols during China’s February 2014 blockade of Philippine resupply of Second Thomas Shoal. They played the frontline role in the 2014 repulsion of Vietnamese vessels from disputed waters surrounding China National Offshore Oil Corporation’s HYSY-981 oil rig.

The militia is a key component of China’s armed forces and its maritime subcomponent is the Third Sea Force of China. China’s maritime militia is a set of marine industry workers (typically fishermen) and their vessels trained, equipped, organized and commanded directly by the local military commands of the People’s Liberation Army (PLA). These units typically answer to the PLA chain of command, and are certain to do so when activated for international-sea incidents pre-planned by Beijing. While most militiamen have civilian jobs, new units are emerging that appear to employ elite forces full-time as militarized professionals. Directed participation by China maritime-militia forces in international-sea incidents or provocations occurs under the PLA chain of command, and sometimes also under the temporary command of the Chinese maritime law-enforcement agencies.

Here’s why the Pentagon’s publicizing of China’s maritime-militia matters: it is strongest—and most effective—when it can lurk in the shadows. But the Naval War College China Maritime Studies Institute’s two-and-a-half-year study—and more than twenty articles, papers and briefings—reveals that there is more than enough open-source information available to expose China’s maritime militia for what it is: a state-organized, state-developed and state-controlled force operating under a direct military chain of command to conduct Chinese state-sponsored activities.

By revealing the maritime militia’s true nature and “calling it out” in public, the U.S. government can remove the force’s plausible deniability, reduce its room for maneuver, and reduce the chances that China’s leaders will employ it dangerously in future encounters with American and allied vessels at sea. The very few previous U.S. government-related statements were not top-level official assessments, and hence did not have the full force and influence of the U.S. government behind them. China’s maritime militia was mentioned by Adm. Scott Swift, commander of the U.S. Pacific Fleet; by Ronald O’Rourke in his Congressional Research Service report on Chinese maritime disputes; and by the U.S.-China Economic and Security Review Commission, which rightly recommended that the Department of Defense address this vital subject. But the Pentagon’s new report is the first official top-level assessment by the U.S. government to cover China’s maritime militia. It is extremely encouraging that the U.S. government has finally brought to bear the full force of its authority and its tremendous analytical capabilities to address this vital issue.